It is well known generally that a polyacetylene can be obtained by, for example, polymerizing acetylene with a Ziegler-Natta catalyst consisting of triethylaluminum and tetrabutyl titanate, as described in, for example, J. Polym. Sci., Polym. Chem. Ed., 12, 11, 1974.
The polyacetylene obtained with the Ziegler-Natta catalyst consisting of triethylaluminum and tetrabutyl titanate, however, has a limit in stretchability and has hitherto shown a stretchability of only about 3-5 times.
In reacting acetylene gas with the above Ziegler-Natta catalyst, the heat treatment of the Ziegler-Natta catalyst at 80.degree. C.-150.degree. C. in an inert gas prior to said reaction gives a slight increase in stretchability of the polyacetylene obtained, but the resulting stretchability is not sufficient.
In view of the above point, the object of the present invention is to provide a polyacetylene with excellent stretchability.